The NYU student could earn an Oscar nomination for his brave and soulful performance in Luca Guadagnino's film — but first, he needs to learn how to button his jacket.

When “Call Me by Your Name” screened at the New York Film Festival last month, several threads from Timothée Chalamet’s 21-year-old life wove together. Above the sold-out, 1,100-seat audience at Alice Tully Hall, he watched the second half from the balcony, seated next to the actor who plays his lover, Armie Hammer, and their director, Luca Guadagnino. Onscreen, Chalamet’s character was 17, the same age he was when Guadagnino met him. At that time, Chalamet was a student at Fiorello H. LaGuardia High School of Music & Art and Performing Arts — the Upper West Side inspiration for “Fame” — across the street.

In kindergarten, Chalamet was a lukewarm commercial actor. His “first moment of passion” for the craft came at age 12, seeing Heath Ledger’s Joker in “The Dark Knight.” “I just had no clue what was going on in his head, and I thought it was the coolest thing in the world,” said Chalamet, holding his perfect trapezoid of chin. It is a Tuesday afternoon at the Sunset Tower Hotel in West Hollywood, and we’re overlooking the rooftop pool.

Once enrolled at LaGuardia (alongside Ansel Elgort and Grace Van Patten), Chalamet later told Columbia University’s student newspaper, Bwog, that he no longer regarded acting as a “machine of fakeness.” Through his mom — a councillor for the Actors’ Equity Association’s governing body — teenage Chalamet caught Philip Seymour Hoffman as Willy Loman in the Broadway production of “Death of a Salesman,” directed by Mike Nichols. Last year, “Doubt” screenwriter John Patrick Shanley handpicked Chalamet to star as a younger version of himself in the Manhattan Theatre Club production of “Prodigal Son.”

Chalament said he identifies as “a theater guy.” Until that Tuesday night in October, “A film experience has never really translated to a theater experience for me,” he said. At the conclusion of “Call Me by Your Name,” a spotlight lit up the balcony. “It very much felt like, weirdly, a play,” Chalamet said. The crowd gave the actors and filmmaker a 10-minute standing ovation, the longest recorded in the festival’s 55 years.

Timothée Chalamet and Armie Hammer in “Call Me by Your Name”

Photo by Sayombhu Mukdeeprom, Courtesy of Sony Pictures Classics

Chalamet is favored to receive a Best Actor nomination, which would make him the youngest contender since Mickey Rooney’s 1939 nomination for “Babes in Arms.” “This has pretty much been the project of my youth,” Chalamet said. Guadagnino and screenwriter James Ivory offered him the role, sans audition, in 2013. They hoped to shoot in 2014, then 2015. “Prodigal Son” closed March 27, 2016, and Chalamet immediately flew to Crema, Italy — where Guardagnino lives — to start six weeks of pre-production, which included piano, guitar and Italian lessons. Production began May 9, 2016.

His character, Elio Perlman, is the only child in a gentle, hyper-literate family that summers in Northern Italy: his father (Michael Stuhlbarg) is a professor, famed for his expertise on Greco-Roman history; his mother (Amira Casar) is a translator. (Chalamet also comes from an impressive clan: his uncle is director Rodman Flender, his grandfather was TV writer Harold Flender, and his aunt, Amy Lippman, co-created “Party of Five” and most recently wrote and produced “Masters of Sex.”) An impish musical prodigy, dark-haired, fine-boned Elio expects to soon lose his virginity to a neighborhood girl (Esther Garrel), sometime between bike rides, late-night swims, and plucking fruit from the trees outside their old-world manor.

But in the first scene, a car deposits a six-foot-five American doctoral student named Oliver, who Elio immediately identifies as “l’usurpatore” (“the usurper”). Elio must vacate his room for the unapologetic, blond visitor with a Star of David necklace (the Perlmans, meanwhile, are “Jews of discretion”). Oliver sees nothing wrong with skipping the first day of meals with his hosts to sleep off his jetlag, or correcting Professor Perlman in front of his family.

“Elio kind of has his homeostasis and his ecosystem that’s very familiar, and his friends like Marzia that come by the house often,” Chalamet said. “That repellant turns into an attraction and the things that were initially unlikeable about Oliver end up being the things that drive Elio crazy about him.”

As the film progresses, Elio is emboldened; he jolts their physical relationship from ambiguous shoulder massages to plain sexual advances. “I felt in the greatest hands with Luca,” Chalamet said. “There was never any sort of anxiety that it would be treated salaciously or exploitatively or shot in a gross or sinister [way].” Following the NYFF ovation, Guadagnino earned more applause during the Q&A when he said, “To put our gaze upon their lovemaking would have been a sort of unkind intrusion.”

When accepting a Hollywood Film Award for his performance November 5, Chalamet told Guadagnino: “I’ll be endlessly thankful and stupefied that you put an actor with so little street cred as myself into a role as layered, and complex, and contradictory, and confused as Elio Perlman.” He also addressed Hammer: “Armie, I’m thankful I have an adult homie in my life now I can call when adult things confuse me.” Next, Chalamet will vie for the Breakthrough Actor Gotham Award. If Guadagnino moves forward with his proposed sequel, Chalamet confirms he would “totally” return.

Chalamet, Steven Spielberg, and Hammer at a New York Film Festival after-party last month

Curtis/StarPix/REX/Shutterstock

Despite being in his second decade in the business — with credits including an eight-episode “Homeland” arc and, like Ledger, a Christopher Nolan feature (“Interstellar”) — he’s far from feeling fully formed. Asked what kind of kid he was, Chalamet replied, “Well, what kind of kid am I?” (The next day, before filming an IndieWire studio interview with Hammer, Chalamet asked him about his jacket: “What’s the man standard, buttoned or unbuttoned?”)

Additional gentlemanly guidance has come from Stuhlbarg, whose acknowledgement of Elio and Oliver’s affair in “Call Me by Your Name” carries absolutely no judgment. “It’s loving and different in how right it is, that monologue, and yet it’s not sappy or Disney-like,” Chalamet said. “He’s the dream father, and we should all be so lucky to have anybody in our life to say that to us.”

Chalamet is a third-generation New Yorker, but his real-life father is from France, and his mother’s roots are in Russia and Austria. They actually did summer in Europe when he was growing up, albeit France, where Chalamet coached youth soccer, and his actress older sister now resides (he interrupted a sibling FaceTime session for our interview, during which she texts, “YOLO COME BACK.” He did, after greeting his “Miss Stevens” co-star and fellow hotel patron Lily Rabe).

He said his time in France led to “a little bit of ambiguity in the self-identity sense, which helps a lot creatively because I don’t feel as constricted by who I am. I almost don’t really know the answer to that.”

Chalamet at the 2017 Toronto Film Festival

TODA/EPA-EFE/REX/Shutterstock

Still, his prolific year translated to three releases — “Hot Summer Nights,” “Call Me by Your Name,” and “Lady Bird,” where he plays the lead’s not-so-compassionate musician fling. As he discusses “Lady Bird,” it highlights the charmingly complicated way Chalamet sometimes speaks: “I’m just thinking of how things look when read, so I speak slowly and just try to pick my words.” Instead of calling his character merely “aloof” or “unlikable,” he said Kyle “has to hit a specific antagonistic note, to some degree — or at the very least it can’t be a smooth part of the narrative — and yet I would hope that the character comes across as a human and even in poor and reckless behavior, someone whose still three-dimensional.”

In 2017, he also shot Woody Allen’s “A Rainy Day in New York” and “Beautiful Boy,” an adaptation of David Sheff’s memoir directed by Felix Van Groeningen. Steve Carell portrays Sheff, the father of a recovering meth addict (Chalamet). Post-“Call Me by Your Name,” he’ll next hit theaters with “Hostiles,” a Western from writer-director Scott Cooper starring Rosamund Pike and Christian Bale.

“I have the tremendous benefit of nobody knowing who I am,” he said, which isn’t exactly true — four years ago, he landed in New York tabloids for dating LaGuardia classmate Lourdes Leon, otherwise known as Madonna’s daughter, and there’s now YouTube footage of him kissing Selena Gomez for Allen’s lens. “Then you can have sex with a peach in a movie” — as he does in “Call Me by Your Name” — “and not be concerned that the collateral you’re putting on the line will be damaged if the performance of the film is no good.”

Now he’s on the precipice of full-fledged fame, but he sees no reason to become jaded. “Sometimes I’ll hear my parents’ friends point out something that’s been said cynically, or a joke that’s been made that’s cynical, and I can’t ever hear it because that’s part of the cultural DNA now,” he said. “‘Call Me by Your Name’ rejects all of that. It’s just a pure celebration of love. There isn’t some dark antagonizer.”

Sony Pictures Classics’ “Call Me by Your Name”will be in theaters on November 24.